Embodiments generally relate to a display drive circuit and a display device having the display drive circuit, and particularly to a display drive circuit which can be suitably utilized as a display drive circuit operable to drive source lines of a display panel.
The rise in the degree of high definition display panels including LCD panels (LCD: Liquid Crystal Display) or organic EL display panels (OELD: Organic Electro Luminescence Display) leads to the increase in the number of outputs of source drivers for driving source lines (also, termed “data lines”) that a display panel has, and makes longer the length of a long side of a semiconductor chip (also, termed “display driver IC (Integrated Circuit)”) having a display drive circuit. For instance, source drivers are arranged along a chip's long side, and they produce analog signals of voltage levels corresponding to display data from gradation lines wired commonly and serving to supply gradation voltages, and drive source lines. With the chip having a larger long side, the gradation lines extending to inputs of the source drivers are longer in their lengths, which consequently increases the parasitic resistance and the parasitic capacitance, worsens the capability of converging of the gradation lines and therefore, causes a delay in the converging time of the source lines.
The Japanese Unexamined Patent Application Publication No. JP-A-2012-255860 discloses a display driver IC which is operable to work at a higher speed, and arranged to have a reduced parasitic resistance and a reduced parasitic capacitance. The display driver IC has a gamma-gradation-voltage-generation circuit operable to generate gradation voltages arranged in a center portion thereof with a group of gamma-gradation-voltage-signal lines (corresponding to the “gradation lines”) wired to extend to the right and left along its long side direction.
JP-A-2008-292926 discloses a circuit which avoids the occurrence of variation in gradation voltages among display driver ICs in the case of driving a display part (display panel) by use of the display driver ICs. The display driver ICs each have a gradation-voltage-generation circuit; gradation reference voltages are uniformized by mutually connecting adjacent display driver ICs' gradation lines corresponding to each other.